The use of carob as a food product for humans has existed since early times. Nowadays it is still used as human food in some countries of the Mediterranean basin from where the fruit originates.
The field of application of the product provided by the present invention corresponds to uses which are similar to those of other sugars, but with an advantage in terms of the low cost of the product of the invention compared with the known sugars and in terms of the re-evaluation of the carob by finding for it a noble and constant application. It is worth remembering that Spain is the leading carob producing country in the world, supplying almost 50% of the world's total, and that it is a Mediterranean dry farming crop.
The fact that it is lower in cost than the sugars obtained from sugar beet, sugar cane and even national maize is of particular importance these days when, with the incorporation into the single European market, Spanish sugar beet and therefore sugar cannot compete with the more economical and higher quality European product. The reason for these lower costs are based on:
Lower raw material cost. To produce 1 kg of sugar about 3 kg of carob pulp are required (14/15 Pesetas/kg), compared to 8 kg of sugar beet (8/9 Pesetas/kg). PA1 Considerably lower investment in installations and equipment. As it is a non-perishable raw material the installation can operate throughout the year. As it is richer in sugar, the volume which has to be processed is lower during the initial stages. PA1 The cost of transformation is no greater. PA1 a) The carob fruit from the field is subjected to mechanical operations to separate the foreign elements, it is washed in water and dried by a current of air; PA1 b) The pods are cut up sufficiently to release the seed, preferably until they pass through a sieve with a hole diameter of 12 to 20 mm; PA1 d) The cut up material obtained in the previous stage is subjected to a separation-sieving operation to separate on the one hand the seeds and on the other the pulp; the pulp being subjected to classification, preferably until it has a granulometry of less than 10 mm; PA1 d) The pulp, cut up to the appropriate granulometry, is subjected to a continuous extraction process in which the pulp is put in contact with diffusion water for the minimum amount of time necessary, in order to avoid the proliferation of microorganisms, to obtain a raw juice, with concentration of between 30.degree. to 50.degree. Brix, and a waste pulp which constitutes the insoluble fraction of the carob pulp; PA1 e) The waste pulp is pressed in order to extract a substantial part of the water it carries, the water still containing in solution sugars and various non-sugars and being recycled for the extraction of sugars in the previous stage; PA1 f) The raw juice obtained in the extraction process is filtered to remove particles of carob fruit in suspension whose size is=25 .mu.m; PA1 g) The juices are decalcified by a cationic resin charged with Na.sup.+ ions; PA1 h) The juices are filtered once again this time through fine filters in order to remove particles whose size is=5 .mu.m; PA1 i) The raw juice is evaporated and concentrated from a concentration of 30.degree.-50.degree. Brix as it leaves the extraction stage to a concentration of approximately 60.degree. Brix; PA1 j) The sugars and non-sugars of the juice obtained in the previous stage are separated chromatographically by passing the juice through a column of strong cationic resin based on weakly reticulate polystyrene and whose active sulphonic groups are charged with a monovalent cation, preferably sodium or potassium, the column then being washed with water to obtain a saline fraction which has a low degree of purity, followed by a fraction which is low in salts and rich in sugars with a high degree of purity, an intermediate fraction being recirculated to the column; PA1 k) The fraction rich in sugars with a high degree of purity is subjected to additional purification by ionic exchange in two phases, the first to separate the dissolved salts and the second to separate the coloring elements, to obtain a juice which is essentially pure and which has a concentration of 20.degree.-25.degree. Brix; and PA1 l) The juice obtained in the previous stage is concentrated to levels of approximately 65.degree.-70.degree. Brix.
The existence of syrups made from carob obtained in southern Italy, Portugal and in incipient form in Spain is known. This product corresponds to the first aqueous extraction of the carob pulp without purification and comprises a mixture of all the elements of the carob pulp which are soluble in water. It is strong and dark in colour, has an unpleasant odour and tastes of a mixture of sugars (sweet) and soluble tannins (bitter), i.e. it still retains the negative characteristics of color odor and taste of the carob itself.
Repeated attempts to find processes of purification by means of applying ion-exchange resins are also known, but these processes have never become reality because they are not economical and have serious contamination problems.
The preparation of crystalline sucrose following the normal methods of the sugar industry gives a low yield due to the interference of the reducing sugars and other impurities which obstruct crystallization and make the process uneconomical.
The crystallization of sucrose from carob has been tried by means of processes other than those normally used for sugars but these too have proved to be uneconomical (Oddo, 1.936; Lafuente, 1.954). Vazquez Sanchez (1.934) precipitated sucrose with alkaline-earth metals but this method did not get past the laboratory stage. The work of Lafuente (1.952) made it possible to avoid the interference of the reducing sugars with the crystallization of sucrose by carrying out a selective fermentation of said sugars using yeasts. This procedure, which could have been economical, violated Spanish law which does not permit the production of alcohol, the product obtained as a result of the fermentation process.
Unable to obtain crystalline sugars, researchers turned to the production of liquid sugars and/or syrups with a high degree of purity. The techniques employed were based on the use of a clarification process which was expensive due to the type of additives which were necessary and the use of ion-exchange resins which were costly and had problems with regenerants. There was a small pilot line at the end of the 1950's (Cortes Navarro, Primo Yufera, 1.961).
After the above mentioned experiences there are no other known technical attempts to solve the process designed to obtain a colorless, odorless syrup which contains all the sugars of the carob in natural form.
By analyzing the chemical composition of the carob pulp it is clear that the nutritional value is concentrated in the water soluble part, since the insoluble part (fiber, cellulose and hemicelluloses) cannot be digested by the human organism. Within the soluble part, the sugars form 3/4 of the dry matter, the cyclitols about 1/10 and the rest, which has little weight, consists of a series of other products which give the first broth its dark color and which give the carob its characteristic odor and flavor, which are not too pleasant according to current tastes.
Given these facts, research was directed to obtaining a natural carob extract from which the negative characteristics of the juice in its natural state, i.e. color, odor and taste, had been eliminated.